/*
package demo1;

public class Computer  {
    public void  powerOn(){
        System.out.println("打开笔记本电脑");
    }
    public void  powerOff(){
        System.out.println("关闭笔记本电脑");
    }
    public void useDevice(USB usb){
        usb.openDevice();
        if(usb instanceof Mouse){
            Mouse mouse = (Mouse)usb;
            mouse.click();
        }else if(usb instanceof Keyboard){
            Keyboard keyboard = (Keyboard) usb;
            keyboard.input();
        }
        usb.closeDevice();
    }

    public static void main(String[] args) {
        Computer computer =new Computer();
        computer.powerOn();
        computer.useDevice(new Mouse());
        computer.useDevice(new Keyboard());
        computer.powerOff();
    }
}
*/
